It was the very first time Jigen was told to wash everyone's clothes, and Lupin meant everyone's clothes. He started off with Lupin's suit, followed by Goemon's. Fujiko didn't trust Jigen to wash her clothes. But you gave him your clothes.

After a few moments later....

Lupin: "Bahahahahahahaha!!! J-Jigen, what are you wearing??!!"

Lupin laughed loudly as soon as he enters the laundry room. Ilaria, Goemon, and Fujiko went to the laundry room after hearing Lupin's laughter....

Jigen was wearing your underwear and One of your large shirts.... Jigen was blushing furiously.